People who spend much time playing video games, especially violent video games, may risk damaging brain functions and affect their learning and emotional control, according to findings of a study released Wednesday.

Chou Yuan-hua, a doctor in the Department of Psychiatry of Taipei Veterans General Hospital, enlisted 30 people -- all aged 25 -- as research subjects.

They were given physical examinations to monitor changes in blood circulation in their brains before and after each played a video game for 30 minutes.

The study found that the act of playing video games obviously causes a decreased blood flow in the brain, and that the effect is even more pronounced in those playing violent video games.

Noting that the study focused on subjects who played video games for only 30 minutes, Chou said many youngsters spend far more time on video games each day, unaware that doing so on a long term basis could damage the frontal lobe of the brain, as well as the anterior cingulate gyrus.

He explained that the frontal lobe of the cerebral cortex, located at the front of the brain, is associated with thinking, speaking, decision-making and impulse control, while the anterior cingulate gyrus, located in the medial wall of the frontal lobe, modulates internal emotional responses.

Although no conclusions have yet been drawn regarding what might happen if blood flow to these brain areas is diminished frequently, it is already known that frontal lobe damage can leave people emotionally adrift, opening them up to odd mood changes and variations in social behavior and personality.

Chou added that clinical experiences have proven that patients with schizophrenia or depression have significantly lower blood flows in their frontal lobes and anterior cingulate gyruses.